Downregulation of myosin heavy chain 9 impairs the mechano-sensing function in small cell lung cancer
Objective To investigate the mechano-sensing function of small cell lung cancer(SCLC)cells and the role of the key protein myosin heavy chain 9(MYH9)in cell anoikis.Methods Using 3 kPa and 12 kPa matrix stiffness hydrogels,the Paxillin area and cell polarization of SCLC cells were compared.At both tissue and cellular levels,the key protein MYH9 was identified from 11 important mechanosensitive proteins.By manipulating MYH9 expression levels through lentiviral knockdown and overexpression,the role of MYH9 in cell mechanosensing function was elucidated.Furthermore,its effect on cell anoikis ability was further determined using flow cytometry Annexin V/propidium iodide(PI)doub-le staining.The two groups of continuous variables were subjected to independent samples t-test,while the comparison among three groups was analyzed using One-Way ANOVA.Results Compared to stiff sub-strates,the adhesion plaque area[(0.79±0.17)vs.(1.68±0.30)μm2,t=8.26,P<0.01]and cell aspect ratio(1.30±0.22 vs.1.81±0.26,t=4.65,P<0.01)of human bronchial epithelial cells on soft substrates were significantly decreased,while the adhesion plaque area[(0.48±0.21)vs.(0.53±0.22)μm2,t=0.51,P>0.05]and cell aspect ratio(1.26±0.20 vs.1.36±0.22,t=1.06,P>0.05)of SCLC cells showed no significant changes.Analysis of transcriptome sequencing data of SCLC tis-sues from the gene expression omnibus(GEO)database revealed significant downregulation of MYH9 protein expression in SCLC cells(0.12±0.02 vs.0.30±0.02,t=11.44,P<0.01).Lentivirus-mediated overex-pression of MYH9 in SCLC cells led to a significant decrease in adhesion plaque area[(0.69±0.21)vs.(1.12±0.43)μm2,t=2.85,P<0.05]and cell aspect ratio(1.37±0.18 vs.1.70±0.34,t=2.72,P<0.05)on soft substrates compared to stiff substrates,and an increased proportion of early apoptotic cells in floating culture[(12.81±1.92)%vs.(4.81±1.30)%,t=7.69,P<0.01].Conclusion Impairment of mechano-sensing function in SCLC cells is associated with significant downregulation of the key protein MYH9.Overexpression of MYH9 restores mechano-sensing function in SCLC cells while attenuating their resistance to anoikis.Key mechano-sensing protein MYH9 holds promise as critical therapeutic target for SCLC.